JS - How to validate if string is a number

javascript check if string contains only numbers
typescript check if string is number
check if string is number java
how to check if a number is float in javascript
check if something is a number in js
javascript check if prompt is a number
check if value is string javascript
how to check whether the given input is string or not in javascript

I try to validate various input strings. Therefore I tried to use regular expressions. Unfortunately all negativ cases match to true as well. How can I sepcify that the regular expression has to match the whole string?

const regex = /(^([0-9]+(.||,)+[0-9]?)$)||(^([0-9]+)$)||(^(.||,)+[0-9]+$)/;

const testSetPositiv = ["34", "45.45", ".7867", "3434,34", ",7834", "546.", "45546,", "0"]

const testSetNegativ = ["wegrger", "3443,34erf", "3443.34erf", ",", ".", "4525tg", "1,211.23", "1.211,23"]


testSetPositiv.forEach(function(value) {
  console.log(regex.test(value));
  //should always return true
})
console.log("----------------");

testSetNegativ.forEach(function(value) {
  console.log(regex.test(value));
  //should always return false
})

parseInt and parseFloat can return numbers even if the string contains letters, check snippet:

const testSetNegativ = ["wegrger", "3443,34erf", "3443.34erf", ",", ".", "4525tg", "1,211.23", "1.211,23"];
testSetNegativ.forEach(function(value) {
  console.log(parseFloat(value));
})

(Built-in) way in JavaScript to check if a string is a valid number , How do you check if a string is a number in typescript? The Number.isInteger() method determines whether the passed value is an integer.


A simple regex solution:

const regex = /^(\d*[.,]?\d+|\d+[.,]?\d*)$/;

const testSetPositiv = ["34", "45.45", ".7867", "3434,34", ",7834", "546.", "45546,", "0"]

const testSetNegativ = ["wegrger", "3443,34erf", "3443.34erf", ",", ".", "4525tg", "1,211.23", "1.211,23"]



testSetPositiv.forEach(function(value) {
  console.log(regex.test(value));
  //should always return true
})
console.log("----------------");

testSetNegativ.forEach(function(value) {
  console.log(regex.test(value));
  //should always return false
})

Java Program to Check if a String is Numeric, How do you check if a string is all numbers? Javascript how to validate input text field for Numbers, Decimal, Uppercase, Lowercase and String data. The following Javascript uses the test() method tests for a match in a string. This method returns true if it finds a match, otherwise it returns false. This is very helpful when testing for Username, password, dollar amounts, etc. in HTML forms.


You can use the Number class to validate a string is a valid number. If it is not a valid number, it will return NaN

Example:

>Number(".23232")
0.23232
>Number(".23232abc")
NaN

Is there a built in way in javascript to check if a string is a , To convert a string loosely to a number which is useful for converting '11px' to 11, for example. parseInt(num) // extracts a numeric value from the // start of the string​  Check whether a value is a number in JavaScript or jQuery [duplicate] Validate numbers in JavaScript - IsNumeric() when cast to a String, is a number and it


use isNaN , (side note "45546," should not be a number)

        const testsetMixed = [34, 45.45, ".7867", "wegrger", "3443,34erf", "546.", "45546,", "0"]


    testsetMixed.forEach(function(value){
       if( isNaN(value)) {
         console.log('not number');
       } else {
         console.log('number');
       }

    })

How to check if string contains only digits in JavaScript , How to force Input field to enter numbers only using JavaScript ? Find all the combinations of the array values in JavaScript · How to Create Dark/Light Mode for  file_download Download the validation code from here. Other JavaScript Validation : Checking for non-empty; Checking for all letters; Checking for all numbers; Checking for floating numbers; Checking for letters and numbers; Checking string length; Email Validation; Date Validation; A sample Registration Form; Phone No. Validation; Credit Card No. Validation


Can use isNan() which returns true if the input string is not numeric

How to check for a number in JavaScript, Numbers are a primitive type in JavaScript, but just using typeof is not I forgot to parse the string into a number when I get the value of “ string  Phone Number validation. The validating phone number is an important point while validating an HTML form. In this page we have discussed how to validate a phone number (in different format) using JavaScript : At first, we validate a phone number of 10 digits with no comma, no spaces, no punctuation and there will be no + sign in front the number.


JavaScript isNaN() Function, The isNaN() function determines whether a value is an illegal number (Not-a-​Number). This function returns true if the value equates to NaN. Otherwise it returns  The isNaN () function determines whether a value is an illegal number (Not-a-Number). This function returns true if the value equates to NaN. Otherwise it returns false. This function is different from the Number specific Number.isNaN () method. The global isNaN () function, converts the tested value to a Number, then tests it.


JavaScript Number isInteger() Method, JavaScript Number Reference. Example. Check whether a value is an integer: Number.isInteger(123) //true. Number.isInteger(-123) //true. Number.isInteger(5-2​)  In Javascript, you can convert a string to number using the Number constructor – which returns a NaN if it is not a valid number. Thus, the following Javascript code tests if a number is numeric: Thus, the following Javascript code tests if a number is numeric:


JavaScript : Checking for all numbers, Javascript function to check if a field in a html form contains all numbers or not. To get a string contains only numbers (0-9) we use a regular  The Number() function converts the object argument to a number that represents the object's value. If the value cannot be converted to a legal number, NaN is returned. Note: If the parameter is a Date object, the Number() function returns the number of milliseconds since midnight January 1, 1970 UTC.